In a heavy-duty pneumatic tire with a low tire profile, a groove cracking (cracking in a bottom of a groove) occurs in a circumferential main groove on its outer side in its tire width direction.
As for a conventional pneumatic tire concerning the above problem, a technology disclosed in Patent document 1 is known. The conventional pneumatic tire (heavy-duty pneumatic tire) includes a carcass with end portions that are bent around a pair of bead cores, a belt that is provided on an outer circumferential side of a crown portion of the carcass, a tread that is provided to the outer circumferential side of the belt, and a plurality of circumferential grooves formed on a tread contact surface and extend in a circumferential direction of the tire. When the conventional pneumatic tire is mounted on a standard rim in a state in which the conventional pneumatic tire is filled with an air pressure of 5% of the maximum air pressure, a curvature radius of a carcass line is small in at least inner circumferential side portion in a tire radial direction of the outermost circumferential groove in a tread width direction compared to those in other portions. However, it is difficult to manufacture a pneumatic tire with a local variation of a curvature radius of a carcass line.    Patent document 1: Japanese Patent Application Laid-open No. H11-180109